1. Field of the Invention
This invention relates to counting scales and more specifically to counting scales having multiple sample receivers utilizing a common electrical load measuring device for measuring the number of the samples and of the unknowns.
2. Description of the Prior Art
Counting scales of the type having a sampling pan and a pan for containing an unknown quantity or weight of a plurality of the same objects contained in the sample pan, are well known in the art. Recent advances in the transducer arts have encouraged many scale designers and manufacturers to incorporate the advantages of an electronic readout in their counting scale designs. The incorporation of an electronic digital readout allows the user of the counting scale to obtain an exact weight or count of the items being weighed without the necessity of interpolating between scale division markings. Also, when wide variations are expected in the weights or numbers of the items being measured, the digital display tends to reduce operator errors in reading and interpolating as compared to a mechanical scale device. Furthermore, it is possible to separate the electronic digital readout from the immediate vicinity of the counting scales when remote readouts are required.
An electrical counting scale is disclosed by Klopfenstein in U.S. Pat. No. 3,557,891. The Klopfenstein counting scale utilizes a single transducer for weighing both a known number of sample pieces of like weight and an unknown number of pieces to be counted. The Klopfenstein counting scale utilizes a differential lever arm length to reduce the mechanical tension forces exerted on the load transducer. Hutchinson, in U.S. Pat. No. 3,667,561, discloses a mechanical scale employing an electronic digital display system and a mechanical leverage structure for reducing the forces exerted on the load transducer. Hutchinson utilizes a spring placed along a distended lever arm for absorbing a large proportion of the load forces exerted upon the load transducer by the load lever system.
Other counting scales employing electronic digital display means are disclosed by Davies et al. in U.S. Pat. No. 3,712,394; Merriam in U.S. Pat. No. 3,561,554; Fathauer in U.S. Pat. No. 3,494,437; Yamanaka in U.S. Pat. No. 3,789,202 and Golding in U.S. Pat. No. 2,918,270. Other weighing devices employing electronic means are disclosed by Ballard in U.S. Pat. No. 2,767,974; Horst et al. in U.S. Pat. No. 2,767,975; Chyo in U.S. Pat. No. 3,047,083; Williams in U.S. Pat. No. 2,918,269 and Howe in U.S. Pat. No. 2,467,752.